Appropriate List permissions and read/write using visual webpart

Question

I am learning SharePoint and just learned how to develop Visual Webparts and read data through CAML and write data also. I have a portal where I have one site collection and under that site collection I have sub-sites where we have different document libraries related to their department..i have managed to give permissions by breaking the inheritance and made department groups..well we just started one project in which are taking "Requisitions" (master-detail) from all more then 600 users across the country. so I made one subsite called "EFormsCenter" which is accessible by "http://portal.mydomain.com/EFormsCenter".

In this site "EFormsCenter" i have created two lists "RequestMaster" and "RequestDetail"...created a visual webpart with girdview and all...took input from user and data writes to master list and detail list. When I log in as site collection administrator I can submit data through form but any other user who logs in cannot submit and and getting

"Sys.WebForms.PageRequestManager Server Error Exception : <nativehr>0x80070005</nativehr><nativestack></nativestack>"

and this shows when I used "developer tools" and in console window it shows otherwise pressing submit button nothing happens. I figured its a permission issue so my question is.

1. How to prevent users not to visit "http://portal.mydomain.com/EFormsCenter"
2. Which permissions I should give to "RequestMaster" and "RequestDetail" libraries so user can read, insert, update and delete through visual webpart form. currently its inherting HOME permissions.

Answer 1

You'd want to make sure the users have Contribute permission to the appropriate lists/libraries. That gives them full CRUD operations.